Method for producing and re-melting compounds having high vapor pressure at the meltig point



July 12, 1960 o. G. FOLBERTH 2,944,975

METHOD FOR PRQDUCING AND RE-MELTING COMPOUNDS HAVING HIGH VAPOR PRESSURE AT THE MELTING POINT Filed Aug. 9, 1956 gateate e s 1: 9

in temp 'amre srability of jthe electric properties; where:

a in WING 'CQMHOWSHA, D THe III-L-V eeniiconclucioi-ebehave'analogoqsly. Hence; 7 D if if 5 semiconductorof yelatively great electr'onmo p bihty also has-a 'relatively great temperaturedependence 9%? Gel? 5011791111, lf, F P W assignfll'wfq ,of it elecffi6condfictanceproperties. Thusgaccdrding lemens m kew t ng la h 'to' remit measurements, an'optimufh electron inobilitv oi about. 65,000 cmFlxZolt. Second. is obtainablerwith in- 10 diuin aritimoni'de (InSbJbut is accompanied by a relative;-

hog. gel; No. 1y g;eati t'eniperanire dependence. For applications re: glaimsnmiofim ppfiga i gg g 15,}? I qninngl least, possible SBHSIHYILY: tochanges 1n temperae ia ns ta lmnd- E la eal Ge y, asanwxatine 9&- fiqmaa llure, if is, preferable tq'use compounds of a wide forbid+ 19; c (CL 51-513 den. zone; that. i compounds corresponding in this re:

' spjedtl toiGelor evenv toSi. "Thus; with indium arsem'de This invention relates to the; production-or remelting nAsllhaving a: foltbiddenrzcn of 0.45 e.v. as mm: of- 'inulti coiiiponent subsqaficew a "iling and patediwith 0.21 ey; QflnSh; a. mu h lesser temperature s'toichiometrio- 'cqm p undsi 1; partit'llarli coiicei fis the Qenendenee han tha tc ifln hvisviobt iae but he. carrier hon ogenining and purifying of sl ich sffib ancs': mqb l v its. mnsmezamy lqwery a ri ly appr x mate y Before proceeding w itha description qf gth enew pr'qc- 20 39 QQ- m-i/volp se n ojn selec s a I I-V com: cases for 11ome 1aim ana pu'rifyin'g;iti"deii'ab1 to pound; etil rmo e lq elv e ated- Ge a Q orbidden describe the field and" Scope of th oce'ssesf'Tliffi'eli mneifthqn l hIml2 flfl lTpegdence i s fu rthe eflgogd, is s''t'forth in'my copendiiigUSTa cation'serialme': but, the cargiep mobility is also'n pch lowel E011 in- 5'54,'361', filed Decer nber' 2bfli95'5 P'a'tnt filo; 2858315, stance, gallium antimonide (GaSb) has a forbiclden gone dfJWhich the instant application isa" cohtinilaitio alzgoyg 0,7 e y. Wiqh;9 f1fQSPQ Q I g; SQb EQilQlY to My" invention re1afces"'genei allyfo seifiicoficllictor aei that ofi; fll le elech-on-n'i ohiligy ie only abpng 3 ,00}! vices. Such devices have acrystalline"body 'of eleclrical egg/vol; geg. 1y oeihiconducting substance subjected 'to'electric or inag n'etic 'fields, go' corpuscular 61 "Wave radiation 61" to a plurality of suchphenomena, for"pei'fonning electrical; photo-electrical, optical or othei physical effects. Examp'le's effsemicendnctiye glevices', Within'the' sdope of my iiivention; are 'tfansistorsf junction 'i'efiifieis, fhe rmist'ofe; detector photo-electric belle," manna-electric juiicfibns; photo-modulators, 'crysnalline' optical filters and other -eptical' co nponents."" 1 V w In the past, emic'onductorl devices have predon inant: ly been provided with a cifi stalline-"body I of gemia'ni'u'xh is fgantamountio deL'cfease-inmeltin g point angl-decl ea se as; in the same sequence, thewam'er mobility 'ifier asesz iii theffourtkgroup ofitheperiodiqfsy'steni; aslthe semi 139 I e conducting elementsdiamondlc) andcig'ray t i 1ii'=(Si1.) I I i ds ts propertieg to the 0p III-V? semiconductdrsjban belookedupon "as being approximate replicas of the semiconductihggfourtmgronp I element's C, Si; Gefsn' with 'respectito vvidthvofi'the for-- hidden zone and lattice spacing. V r

' When considering the" physical prope -ties, par ticularly those relating to semiconductance, ofil'th'e individual a fourth-group elerhentsi-in their atom-nmnberaseqilence:

C "SiQGe; Sn, it" appears rthat relative to afiy iofle particular pljopel' yfsiich" asifoi'bidd enzon ezwith, lattice spacingor melting point, thisp'rope'rty difiierffrpm elev I jgf fii; meiittoelemfit'in the sarne s' ensel'ofihpi'ogression}New,a .7

' oilsly available discretepropertieaofithefoun elementary se'rniconductois a variety of intermediateplopemivalues thus' affording a greater "choice; It-niiistbieiconsidercgl, however, fhat certain physicalproperties; sucli aslwigith 1' a V v v v o'fthe forbid den'zone andcairir mobility} in inuif fanned-pg nAs'anQQaAaon compositions (In Ga ,Q'Ri tiially inverse 'relationfromfdni'th gfoup elemefil lfio ele fofifiiil' o f IiiP ariii GaP inent nd also from LII-V:compoundfio-coifipofiiiglf'l oi" v H er, according to another feature of my inven v y I 3 the third group in common. This mixed crystal is of the type A (C,,D wherein A is an element of the third group, C and D are difierent respective elements of the fifth group, and the subscripts denote atom pro: portions, the value of y being larger than zero and smaller than unity. Mixed crystals of this type form themselves readily from a melt of the components and canreadily be processed and. used in practice in much the same manner as the IIIV compounds themselves.

It is known that two elements "U and V which are isomorphous as well as soluble in each other in the solid state, may form mixed crystals within a continuous range of composition. This has been observed for such alloys as Ag -Au, Sb-Bi and GeSi. Within that range of composition, the respective properties of such mixed crystals show a continuous change, depending upon the particular proportions of thecomposition, from the properties of the pure element U to the properties of the pure element V. This has also been observed, relative to forbidden zone and carrier mobility, with mixed crystals of the type Ge sl x formed by the semiconducting elements Ge and Si. However, the existence of mixed crystals of semiconducting III-V compounds was not known, and the utility and advantage of such compound mixed-crystals for use in electrical, photo-electrical, optical and the like semiconductor devices was likewise unknown.

I further discovered that the IIIV compound mixed crystals can be produced from a melt and can be processed substantially in the same manner as the elemental semiconductors or the individual IIIV semiconductor compounds themselves. crystals can be purified, homogenized by tempering, or can be processed toward monocr'ystalline structure, for instance by zone melting, melting and normal freezing (oriented solidification), or pulling a monocrystal out of the melt.

germ or seed in contact with the melt of the compound mixture and then pulling the seed away from the melt at the speed of crystallization so, that a monocrystal of the desired mixed type will grow on the seeds ILfound doesnot result in decomposition or segregation ofthe mixed crystal, and also that the mixed crystals canlbe.

doped with substantial impurities (lattice-defect atoms),

For instance, a monocrystal can be produced in the known manner by placing a monocrystalline That is, the compoundrnixed forinstance as needed for producing pen junctions. Dopr ing the crystal with an element of the second periodic group, preferably cadmium or zinc (acceptors), produces p-type conductance. Elements of the sixth group, preferably sulphur, selenium or tellurium, act as donors, i.e. produce n-type conductance.

I have found that among the compound mixed crystal semiconductors according to the invention those of the types In (As P and Ga (As P are particularly advantageous. Mixed crystals of such compositions can readily be produced by melting in each case the two component compounds together or by producing a melt from a mixture of three elements in the proper atomic proportion. The mixed crystals can further be readily subjected to any of the above-mentioned processing methods. 7 In comparison with the semiconductor compounds InAs and GaAs as such, the width of the forbidden zone and hence the temperature dependence of the electric properties can be considerably modified by the selection, of the amount of phosphorus. Consequently, for any particular application of the semiconductor device the most be tailored as to its properties to definite predetermined values.

This application is an improvement of or modification of the invention described in the pending U.S. application Serial No. 534,852, filedon September 16, 1955, in

t at Vthe melting, Zone melting rorkorthr heat treatment assig ed to the asslgnee of the present rnvention.

4 V which the instant applicant is joined with another. I incorporate by reference all of the subject matter found in Serial No. 534,852 into the instant application. That application relates to a method for producing an alloy or compound in crystalline form by melting the components together within a sealed system, the compound or alloy being such that in condition of equilibrium the partial vapor pressure of one, or more, components above the melt is considerably higher than the partial vapor pressure of the other component, or components, and is also considerably higher than the partial vapor pressure of a gaseous compound formed of these components.

The method according to the said copending application Serial No. 534,852 represents an improvement over the Faraday method and differs therefrom by the fact that the weighed-in quantities of the components as well as the temperature program are so chosen that, on the one hand, the melt can take the desired proportion of the lowvolatile component out of the vapor phase and that, on the other hand, the remainder of this componenh or components, is just sufficient to form the share of this component, or components, of the equilibrium vapor phase above the melt so that there is no residual or bottom body of the low boiling or more volatile component, or components, on the bottom of the processing vessel at the termination of the melting operation. As a result, and in contrast to the Faraday method, it is not necessary to maintain the temperature of the coldest spot of the melting vessel at an accurate value; and the processing becomes independent of the complicated vapor-pressure conditions obtaining with polymorphous conversions of the bottom body. Said copending application Serial No. 534,852 also describes the application of this process to zone melting.

The present invention has for its further object to provide a method which is suitable for homogenizing and purifying of compounds and alloys composed of more than two components, particularly components having a wide range of existing concentrations. Among such compounds are, above all,-the mixed crystals formed by A B compounds as described in my copending application Serial No. 554,361, filed December 20, 1955, arlrld T e term Wide range of existing concentrations of a compound or;-alloy, particularly a mixed crystal, means that the range of existence relative to at least two of the components is wide 'with respect to the relative concentrations or proportions which these respective components may assume in'the mixed crystal. J The present invention will be specifically decribed in reference to the mixed crystal, In(As P However, the invention has wider scope and implication, since it includes all of the manifold examples, species and classes described in my copending application Serial No. 554,361. For example, this further includes elements from group six, such as sulfur, selenium, and tellurium as the more volatile component.

. For producing a mixed crystal of the composition In(As P the apparatus illustrated on the drawing may be employed, this device being identical with the one described in US. application Serial No. 534,852. Accurately weighed quantities of 15,090 grams indium (In), 7,893 g. arsenic (As) and 0.870 g. phosphorus (P) are sealed into an ampule'l of quartz of '60 cm. volume. The indium is placed in a carburized boat 2 of quartz. The weighed amount of arsenic and phosphorus may be located on any other free spot .on the bottom of the quartz'ampule. The sealed and fused-off quartz ampule is placed in a two-temperature furnace which is equipped with a high-frequency induction heater 4 located in the center range of the ampule for heating the indiumcontaining boat, and two resistance heaters 5- so located as to maintain the end portions of the ampule at an elevated temperature@ The melting is carried out as described in US. application Serial No. 554,361,

. w? hh hw n h a As ratio Wh. h 39 amen ran: Q- 2.85 T hca i h ed-b h hi qhencv duct o il 4 to a t mh hr f h 960? 'C., and the other parts of'the anpuie are kept at about 700 C. by means of the heaters5', Q. As a result m t. Pr du ed n t boat. w chh h hom h 5 L IA M OQ). a d th r s a o. fo med" h h me ming vapor phasewithout any bottom bodyreni laining of h ei hed-in owola e cm hhe t i P If h melt we P rmitted o so idify l i P s from one end, as in normal eezing, then a crystal would liqformed, whose first so dend contains morepho's-f nh 'rus o he app a hla. mp s n n( o. 0.3). and whose la sol i ed end con a m e h s c f example of the approximate composi ion 1 1( o.t 0.1)- uch rys l a 9 d ub desira le r $94 1? apnations. Generally, however, it is preferred to ohtain homo e e c y als rom he melt" A rd ng t th n'resenl invemion h s s ac sfo lows;

'Ihhmeh pr du ed E1Ilb$1 ah ve is. i st ause o rapi y s lid in an unh'rihtqsl mann r; the S eed o h fich ihn b i so re haoa ho he hhys l h 11 la i e. s r hhir y h re h ural iewpoint; the s ifh l q r m h ma Q QPi or hhrse ltrhthlh ei h N'qwi order to a... o bt in a hhh c eqhsfiherstm h a a f the rocessi g ep mployd h90 9 'Whiah.

he solid fied c s a' i s b cted. o Qheh na ow melting z ne. pr erhh y' h' we hii e mutu l y oppos d sli e i hs t mel hg 29 hh ihg hniwer; hbrf xahrllthhhhhified"distal I t e a e th ihea ih l z' h p rtih b the le th;

th -t me star ih at he ri h th e t. d h th sihahn'r h 'eheohs m xed crysta Whl1 theh mpo it qh 1 .f$o.a. 9-2 very small remainder which appro the w dt f h me in 0h. A. m xed crystal produ ah ie h manne a tihna zohcl a Dh iha "similarity to the above-dc lh al hem? .h n-

. h nd f the ystal;hlhrihh ehhews hail; h crystal latt ce shhctha a an? as soli hd mor a sen c w l. 9 H the original composition Of 6 f owin Zone-melting t p; ther .sn .d talt a sift y iiqi p Pha a t this "vaporous phase in equ br' s iii ifi t. zone! Sia on .9 oth d, pres ur l o in a e th ircah hal? .tsht the m th fi st emot nze h hs he. seqa d ehjee mel step gives h o he W9: 'hh e mo e P than it takes As iro'm the-vapor phase. Qonsequently thernelt now. contains more In than correspondshto the original chm o t r ha he o eqhh e ha hdihh 99.- an ns c u h c ystal a. he h oh z h mehinasth th i h h ro esses 1911 o h and (of the ho el th sqnd i h bec me rev rs he n hftahe ip mo e P ndlif qm th i po ous pha e'than corres'p o 'qr a c rnmg solidificationfthere will t i bn th e th td y .o'ccnr. vapor inc usionsfwi hrn th crystals. Therefore, a

mi e r al h c h s b en .j hh hh o times in the. above-'descrihedmanner, exhibit sindium inclusions. at Qne'end and i s. porous at the other end. Only the rniddle portion of ,the'cry stal possessesthe desired homogeneous composition andcons'istence.

In certain cases the above-described purifying. method. is. not satisfactory. For one thing, only. part ofithe original crystal can be used. Furthermore, thepurifying. effect of the zone-melting is not fully utilized because this efiect is a maximumin' one ofithe crystal endswhich inthe present caseis of no use. 'In such. cases, and. in. accordance with another feature of. the. invention, the. following method may he applied:

In order to produce a mixed. crystal according. to the foregoing example, that is generally at the'type.

the two binarycompounds. and are individ ally produced. according to the Welker Patent 2,798,9229; re; ferred t bove. a d. arepur fi dby one me t n Theh thflmixed ystal is p o uced fro t cse two compoun heating in. an ampule in the manner described in Q application Serial No, 5 4, 6 and i homochn sslas. described above. It is inessential that in this case, when ing the. amounts. or the compon nt the th e ponents are present in the form of chemical compounds. The. same method appli ab e w t compound or alloys having more than two components,

Like. the method. des rib d n W l er Patent 2 7. .9, .89, 'p csent inventi n ca b app ed o he oduc ion of mono-crystals with or without crystal germ. ly the. addition of proper quantities of foreign. substances, any" si ed pin o h c s to he hqh d o Iiilted can beobtainedQ I tha been. fa dab ve t the me ho aqqq dh o he ven on i nerall T PP lQQ for hq ehll h i and puri yin mixcdhry tah. Rf A 1 o ound fi rom h abo e-men oned ex m e nostata.

me hqs sra c la vo a e QF mixed: r a s 9 i he time G@1.(A.SYP'1Y)' a AMAalfii W h .y. F r e m he me ho i ene all I. cable t mu ti-ccm h s ems th t i S st s. W h our n more m ohehts ha ih de. ape? o QIF S ns concen t o s. p vi dt c m onen at sf the ab ve-m tio ed u ement as. o qletil t lql hh 5A m th d o Preachin a hh t me of he swan consis in h m h n h al e o mo a we components. in crystalline form comprising melting the om onen s t ether w th a cal d s ste h Pa ap P essu e o at least e mment e'h e the melt in the state of equilibrium being-considerably higher han. hshan a WP h ehre h he er e m h a h sh i hr' ah th v -ti hre sh a? a g us o of these components, there beingno b1 h Bod of any agtne' low-boiling, re volatile hhiphhemilzr s at thh e h ih'afi h mel h operation. the melt lacing therafter made to solidify rapidly and in an ,uno 'en'ted 'manner; the speed-of solidi: fi fiqn be n h h tf hh a who h h s Qha hQW eP ih ia hwh h' ut ith a c tal ne lath e' Sa m e heter gncqu's' from the fine rugtur'al yi wpoint'. an bhingsubsequ ently zone mann ng nar; rpwfriielting zonei the melting zone having a width. qt a; mostaboutv one-fifth the axial le ngth of the substance, method accordingto "claim :1 in which the Zone melting in 'a narrow melting zone is carried out cessively in two mutuallyopposed directions to homoge; nizethpiddujqt. i 3- "A hhth e dih la 2 t 9l8 Z9 hrahhh h ih h e h hurifieljii by e ti h 12s m in 4. A method according to claim 1 in which the corn: pnn entsof the substance to be processed are hinary,

' '5 A "m ethod according to claim 1 applied to alloys ctmoprisin}; mixed crystals.

Q A me h .ih u i a mixed r st shah oond uctor body taken from the group consisting of those of the formula (A B )mC and those of the A (C D where .A and B are component eleinents of the third group, and C and D are component elements of the fifth group of the periodic system and x and y are each greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and'in an unoriented manner in the sealed system, the speed of solidification being suflicient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone melting said body in' a narrow melting zone in a sealed system successively in two mutually opposed directions to hotrio enize the product.

The process of claim 1, the said substance being a semiconductor compound.- I

8. The process of claim 1,- the said substance having a mixed crystal of a plurality of semiconductor compounds. 9. A method for producing a mixed crystal semieonductor body of the formula In (As P in which y is greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher" than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an u'noriented manner in the sealed system, the speed of solidification being sufiicient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone melting said body in a narrow melting zone in a sealed system successively in two mutually opposed directions to homogenize the product.

'10. A method for producing a mixed crystal semiconductor body of the formula Ga- (As P in which y is greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solidification being suflicient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine structural view-point, and subsequently zone melting said body in a narrow melting zone in a sealed system successively in two mutually opposed directions to homogenize the product.

11. A method for producing a mixed crystal semiconductor body of the formula Al (As P in which y is greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solidification being suflicient to obtain a body having a structure which is quasi-homogeneous macroscopically butwith a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone melting said body in a narrow melting zone in a sealed system successively in two mutually opposed directions to homogenize the product.

12.,A method for producing a mixed crystal semiconductor body of the formula (In Ga )Sb in which x is greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solidification being sufiicient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone melting said body in a narrow melting zone in a sealed system successively in two mutually opposed directions to homogenize the product.

13. A method for producing a mixed crystal semiconductor body of the formula (In Ga )As in which x is greater than zero and less than one, by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higherthan the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements prescut at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solid i-' fication being sufiicient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structure viewpoint, and subsequently zone melting said body in a narrow melting zone in a sealed sys tern successively in two mutually opposed directions to homogenize the product.

14. A method for producing a body comprising a semiconductor compound by melting component substances forrning said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solidification being sufficient to obtain a body having a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone v l t ling said body in a narrow melting zone in a sealed system successively in two mutually opposed directions to homogenize the product.

15. A method for producing a body comprising a mixed crystal of a plurality of semiconductor compounds by melting component substances forming said body within a sealed system, the partial vapor pressure of at least one component element above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of another component element and considerably higher than the partial pressure of a gaseous compound of these component elements, there being no bottom body of any of the low-boiling, more volatile component elements present at the termination of the melting operation, the melt being thereafter made to solidify rapidly and in an unoriented manner in the sealed system, the speed of solidification being sufiicient to obtain a body having a structure which is quasihomogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and subsequently zone melting said body in a narrow melting zone in said sealed system successively in two mutually opposed directions to homogenize the product.

16. A method for processing a substance of the group consisting of compounds and alloys of more than two components in crystalline form comprising melting the components together within -a sealed system, the partial vapor pressure of at least one component above the melt in the state of equilibrium being considerably higher than the partial vapor pressure of the other component and considerably higher than the partial pressure of a gaseous compound of these components, there being no bottom body of any of the low-boiling, more volatile components present at the termination of the melting operation, themelt being thereafter made to solidify rapidly and in an unoriented manner, the speed of solidification being sufiicient to obtain a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and being subsequently zone melted in a narrow melting zone, the melting 'zone having 'a Width of at most about one-fifth the axial length of the substance,

said substance being composed of at. least one component taken from the group consisting of boron, aluminum, gallium, indium, and at least one component fromthe group consisting of nitrogen, phosphorus, arsenic, and antimony, and all of the components being taken from the said two groups. a

' 17. A process for producing a mixed crystal of the composition In (As P in which y 1, the method being carried out in a melting and vaporizing space that is sufliciently enclosed to prevent egress of the vapor evolved in theprocess, comprising melting indium in a zone of said space, vaporizlng arsenic and phosphorus in said space but separately from said melting of the indium, the proportions of the indium, arsenic and phosphorus being so chosen that there is no residual solid body of the arsenic and phosphorus at the termination of the melting operation, then causing the melt to rapidly solidify in the said space in an unoriented manner, the speed of solidification being sufficient to obtain a structure which is quasi-homogeneous macroscopically but with a crystalline lattice structure heterogeneous from the finestructural viewpoint, and thereafter zone melting in a narrow melting zone in two successive and mutually opposed directions.

18. A process for producing a mixed crystal of the composition Ga (As P in which 0 y 1, the method being carried out in a melting and vaporizing space that is sufficiently enclosed to prevent egress of the vapor evolved in the process, comprising melting gallium in a zone of said space, vaporizing arsenic and phosphorus in said space but separately from said melting of the gallium, the proportions of the gallium, arsenic, and phosphorus being so chosen that there is no residual solid body of the arsenic and phosphorus at the termination of the melting operation, then causing the melt to rapidly solidify in the said space in an unoriented manner, the speed of solidification being suflicient to obtain a structure which is quasihomogeneous macroscopically but with a crystalline lattice structure heterogeneous from the fine-structural viewpoint, and thereafter zone melting in a narrow melting zone in two successive and mutually opposed directions.

-19. A process for producing a mixed crystal of the composition A1 (As P in which 0 y 1, the method being carried out in a melting and vaporizing space that is sufficiently enclosed to prevent egress of the vapor evolved in the process, comprising melting aluminum in a zone of said space, vaporizing arsenic and phosphorus in said space but separately from said melting of the aluminum, the proportions being so chosen that there is no residual solid body of the arsenic and phosphorus at the termination of the melting operation, then causing the melt to rapidly solidify in the said space in an unoriented manner, and thereafter zone melting in a narrow meltingzone in two successive and mutually opposed directions.

References Cited in the file of this patent UNITED STATES PATENTS 2,710,253 Willardson June 7, 1955 2,739,088 P fann Mar. 20, 1956 2,776,206 Klingbeil Jan. 1, 1957 2,798,989 Welker July 9, 1957 2,817,608 Pankove Dec. 24, 1957 FOREIGN PATENTS 111,288 Great Britain May 9, 1918 

6. A METHOD FOR PRODUCING A MIXED CRYSTAL SEMICONDUCTOR BODY TAKEN FROM THE GROUP CONSISTING OF THOSE OF THE FORMULA (AXB1-X)IIIC1V AND THOSE OF THE FORMULA AIII(CYD1-Y)V, WHERE A AND B ARE COMPONENT ELEMENTS OF THE THIRD GROUP, AND C AND D ARE COMPONENT ELEMENTS OF THE FIFTH GROUP OF THE PERIODIC SYSTEM AND X AND Y ARE EACH GREATER THAN ZERO AND LESS THAN ONE, BY MELTING COMPONENT SUBSTANCES FORMING SAID BODY WITHIN A SEALED SYSTEM, THE PARTIAL VAPOR PRESSURE OF AT LEAST ONE COMPONENT ELEMENT ABOVE THE MELT IN THE STATE OF EQUILIBRIUM BEING CONSIDERABLY HIGHER THAN THE PARTIAL VAPOR PRESSURE OF ANOTHER COMPONENT ELEMENT AND CONSIDERABLY HIGHER THAN THE PARTIAL PRESSURE OF A GASEOUS COMPOUND OF THESE COMPONENT ELEMENTS, THERE BEING NO BOTTOM BODY OF ANY OF THE LOW-BOILING, MORE VOLATILE COMPONENT ELEMENTS PRESENT AT THE TERMINATION OF THE MELTING OPERATION, THE MELT BEING THEREAFTER MADE TO SOLIDIFY RAPIDLY AND IN AN UNORIENTED MANNER IN THE SEALED SYSTEM, THE SPEED OF SOLIDIFICATION BEING SUFFICIENT TO OBTAIN A BODY HAVING A STRUCTURE WHICH IS QUASI-HOMOGENEOUS MACROSCOPICALLY BUT WITH A CRYSTALLINE LATTICE STRUCTURE HETEROGENEOUS FROM THE FINE-STRUCTURAL VIEWPOINT, AND SUBSEQUENTLY ZONE MELTING SAID BODY IN A NARROW MELTING ZONE IN A SEALED SYSTEM SUCCESSIVELY IN TWO MUTUALLY OPPOSED DIRECTIONS TO HOMOGENIZE THE PRODUCT. 